The described invention relates in general to manufacturing systems and methods and more specifically to a system and method for applying ultrasonic excitation to segmented dies used in manufacturing processes such as those used in the automotive industry.
The potential of using ultrasonic vibrations to reduce friction during sheet metal forming processes, e.g. in deep drawing, has been recognized and investigated over the years, with favorable results having been reported, both in forming processes, and in the fundamental mechanics of friction reduction. One sheet metal forming area where ultrasonic friction reduction would presumably have a major benefit is in the forming/stamping of auto body parts. In this field, new challenges are continually emerging as efforts are made to form higher strength steel and aluminum alloys having complex shapes. However, in forming and stamping of auto body parts and the like, large steel dies, blank holders and punches are used, not uncommonly having weights in excess of several thousand kilograms and lateral dimensions on orders of meters and of significant thicknesses. Unfortunately, achieving ultrasonic excitation of such large masses is beyond the current capabilities of high power ultrasonic systems and would seemingly rule out this field of application. Furthermore, current industry methods for friction alleviation typically involve the application of coatings to a die surface, which has the disadvantages of (i) requiring renewal as it wears away with repeated stampings; (ii) leaving residues on the stamped sheet metal surfaces which must be later removed; and (iii) the subsequent disposal of those residues.
However, three primary factors suggest that there are significant applications for high power ultrasonics (HPU) in the forming of auto body parts and the like. First, in the stamping of auto parts, it has been observed that only certain critical areas of a die are unusually challenging to the forming operation. Thus, while a die may indeed be of large size and mass, only a comparatively small region might have a form or shape factor that may compromise die performance. Accordingly, the amount of die volume/mass associated with a problem region could be within a range that could be feasibly vibrated by ultrasonic vibrations, provided that region could be acoustically isolated from the remaining die mass. Secondly, it is current practice to segment portions of a die for various purposes, but most notably to permit repair or replacement of high wear regions. Although it would seem that the boundaries of the segmented regions would be susceptible to causing marking of the stamped parts, the stamping process is actually fairly tolerant of die surface details insofar as part markings Thirdly, through prior work on ultrasonic friction reduction, processes have been developed for acoustically isolating and securing ultrasonically excited blocks that are believed able to find application to the present issue of both ultrasonically vibrating a die segment and securing it within an overall die structure. Thus, there is an ongoing need for a system for applying ultrasonic excitation to segmented dies.